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United States Patent |
5,325,114
|
Fogle
,   et al.
|
June 28, 1994
|
Thermal printing postage meter system
Abstract
The thermal printing postage meter includes a base supporting a
registration wall and a deck, and a thermal print head mounted to the
registration wall above a portion of the deck to define a print station. A
position sensing assembly is provided for sensing the presence of the
envelope's leading edge in the print station and informing a
microcontroller. A thermal tape cassette is mounted to the registration
wall such that a portion of the thermal ribbon passing below the thermal
print head. A platen roller assembly and position assembly are responsive
to instruction from the microcontroller for causing the platen roller to
assume either a position biasing the envelope against the thermal ribbon
and thermal print head or a retracted position. An ejection roller
assembly having position assembly is responsive to instruction from the
microcontroller for causing the ejection roller to assume either a
retracted position or a position biasing the ejection roller against the
envelope and an ejection plate. A motor which is responsive to the
microcontroller causes the platen roller or the ejection roller to rotate.
The microcontroller is programmed such that in response to activation of
the position sensing means by the envelope, the microcontroller causes the
platen roller assembly to bias the envelope and to initiate print sequence
instruction to the print head while synchronously causing the drive means
to cause the platen roller to rotate at a first speed. Upon completion of
the print sequence, the microcontroller causes the platen roller to assume
a retracted position and the ejection roller assembly to assume a biasing
position and causing the ejection roller to rotate at a second speed for
envelope ejection.
Inventors:
|
Fogle; Ronald L. (Springboro, OH);
Mistyurik; John D. (Troy, OH);
Porter; Lorraine T. (Dayton, OH);
Strausburg; Larry D. (Waynesville, OH)
|
Assignee:
|
Pitney Bowes Inc. (Stamford, CT)
|
Appl. No.:
|
950341 |
Filed:
|
September 24, 1992 |
Current U.S. Class: |
347/220; 101/76; 101/91; 347/214; 347/222; 400/208; 400/582; 400/583.4; 400/649; 400/708 |
Intern'l Class: |
B41J 002/315; B41J 015/04 |
Field of Search: |
346/76 PH
400/120
101/76,91
|
References Cited
U.S. Patent Documents
4605937 | Aug., 1986 | Dolan et al. | 346/76.
|
4746234 | May., 1988 | Harry | 400/120.
|
4938129 | Jul., 1990 | Miciukiewicz | 101/76.
|
Primary Examiner: Fuller; Benjamin R.
Assistant Examiner: Tran; Huan
Attorney, Agent or Firm: Parks, Jr.; Charles G., Scolnick; Melvin J.
Claims
What is claimed is:
1. A thermal printing postage meter having a base supporting a registration
wall and a deck, and a thermal print head fixably mounted to said
registration wall above a portion of said deck to defining a print station
for printing a postage indicia on an envelope having a leading edge
positioned on said deck in said print station, comprising:
a position sensing means for sensing the presence of said envelope's
leading edge in said print station;
a microcontroller in bus communication with said position sensing means;
a thermal tape cassette having an opening a thermal ribbon, said thermal
tape cassette detachably mounted to said registration wall such that said
thermal print head extends through said opening and having said thermal
ribbon passing below said thermal print head;
a platen roller assembly having a platen roller and a positioning means
responsive to instruction from said microcontroller for causing said
platen roller to assume a second position biasing said envelope against
said thermal ribbon and said thermal print head, and a home position
ducked below said deck;
an ejection plate fixably mounted to said registration wall;
an ejection roller assembly having a pressure roller and a positioning
means responsive to instruction from said microcontroller for causing said
pressure roller to assume a home position biasing said ejection roller
assembly towards said ejection plate and a second position ducked below
said deck;
motor means in bus communication with and responsive to said
microcontroller for causing said platen roller and said pressure roller to
rotate under the control of said microcontroller;
said microcontroller being programmed such that in response to activation
of said position sensing means by said envelope, said microcontroller to
cause said platen roller assembly to assume said second position and said
ejection roller assembly to assume said second position and to initiate a
print sequence instruction to said print head while synchronously causing
said motor means to cause said platen roller to rotate at a first speed,
following completion of said print sequence, said microcontroller to cause
said platen roller assembly to assume said home position and said pressure
roller assembly to assume said home position and causing said ejection
roller to rotate at a second speed.
2. A thermal printing postage meter as claimed in claim 1 further
comprising stop means for preventing said envelope from being
mis-positioned longitudinally on said deck.
Description
BACKGROUND OF THE INVENTION
The present invention relates to thermal printing postage meter.
It is an object of a conventional printing press type postage meters to
print a postage indicia on a present envelope characterized by producing a
postage indicia of consistent print contrast across the printed indicia.
Additionally, it is an objective of a conventional printing press type
postage meter to obtain suitable print quality in the specified printing
area for envelope of varying paper grades (i.e., smoothness), porosity and
envelope contour in the printing area.
Of particular note is the effect of the envelope contour in the printing
area on print quality. It is a requirement, for example, by the United
States Postal Service, that the postage indicia be printed in the upper
right corner of the envelope. The contents of a particular envelope can
cause this area to assume a variety of contour characteristic due in large
part to the thickness of the contents and the particular shape of the
contents.
Conventional thermal printers have required a relatively flat surface in
the print area in order to insure adequate print quality. Also, sufficient
time must be allowed for ink transfer which is a function of the
smoothness and porosity of the printing media. Hence, the difficulty in
applying thermal printing technics to postage metering mailing machine and
like applications. That is, in order to obtain suitable print quality, the
conventional thermal printing postage meter requires that the envelope
characteristic be within a narrow range. As a result conventional thermal
printing postage meters have not been able to adequately provide a printed
postage indicia on an envelope having the requisite print quality over a
preferred range of envelope paper smoothness, porosity and contours at
desired speeds suitable for board postage metering mail applications.
SUMMARY OF THE INVENTION
It is an object of the present invention to present a postage meter
printing apparatus utilizing thermal printing technics having a suitable
configuration to print an improved postage indicia of consistent print
contrast across the printed indicia.
It is a further objective of the present invention to present a postage
meter printing apparatus utilizing thermal printing having the capability
of printing a consistent contrast indicia for a range of envelopes of
varying paper grades and porosities.
It is a still further objective of the present invention to present a
postage meter printing apparatus utilizing thermal printing technics
having the capability of printing a consistent contrast indicia on
envelopes having within a range of envelope contours in the printing area.
The thermal postage meter is comprised of a number of system modules. Upon
the placement of an envelope on the deck of the thermal printer by an
operator, the envelope is cause to encounter a position sensing assembly
which includes an envelope stop arrangement. The envelope stop arrangement
prevents the envelope from being longitudinally mis-positioned. Upon
proper positioning of the envelope on the deck, the position sensing
assembly senses the presence of the envelope and inform a microcontroller
to first duck the position sensing assembly out of the way, inclusive of
the stop assembly, and initiate the print sequence. Upon initiation of the
print sequence, a platen roller assembly is repositioned to bias the print
area of the envelope into contact with the print ribbon of a ribbon
cassette. The thermal print head of the postage meter is positioned to
also serve as a backing to the print ribbon. The microcontroller issues
commands to the motor controller to cause a motor to then drives the
platen roller. Rotation of the platen roller causes the envelope and
cassette print ribbon to simultaneously traverse the print head while
concurrently enabling the thermal print head. Following completion of the
print cycle, the microcontroller causes the platen roller to be ducked
below the deck and a pressure roller to be engaged for ejection of the
envelope.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partly section frontal view of a thermal postage meter and
ribbon cassette in accordance with the present invention.
FIG. 2 is a schematic of a microcontroller in accordance with the present
invention.
FIG. 3 is a sectioned top view of the thermal postage meter in accordance
with the present invention.
FIG. 4 is a sectioned end view of the thermal postage meter in accordance
with the present invention,
FIG. 5 is a top sectional view of the thermal postage meter in accordance
with the resent invention.
FIGS. 6A and 6B are side prospective views of a portion of a position
sensing assembly indication, respectively, an initial and ducked position
in accordance with the present invention.
FIGS. 7A and 7B are side prospective views of a portion of a stop assembly
indicating, respectively, an initial and a ducked position in accordance
with the present invention.
FIGS. 8A, 8B and 8C are schematic views of the platen and pressure roller
assemblies in the home position, print position and eject position,
respectively.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, a thermal postage meter, generally indicated as 11,
includes a base 13 which supports a deck 15. The base 13 supports a
registration wall 17, by any conventional means, to extend vertically
upward from the deck. A thermal print head 19 is fixably mounted, by any
conventional means, to the registration wall 17. The registration wall 17
has mounted thereto a thermal ribbon cassette 21. Mounted in the base 13
is a position sensing arrangement, generally indicated as 24, for sensing
the position of an envelope 25 positioned on the deck 15 such that a
leading portion of the envelope 25 is aligned to a platen roller assembly,
generally indicated as 26.
Referring to FIGS. 1 and 2, the thermal printing meter is under the
influence of a system microcontroller, generally indicated as 28. The
microcontroller system 28 is comprised of a programmable microcontroller
30 of any suitable conventional design, which is in bus 32 communication
with a suitable motor controller 34, sensor controller 36, and thermal
print head controller 38. The motor controller 34, sensor controller 36
and thermal print head controller 38 may be of any suitable conventional
design. The motor controller 34 is in motor bus 40 communication with a
plurality of drive motors 42, 44 and 46. The motor control bus 40 also
communicates the motor controller 34 to a tape encoder 48. The sensor
controller 36 is in sensor bus 50 communication with a plurality of
sensors 52 to 55 and the thermal printer controller 38 is in print head
bus 58 communication with the thermal print head 19.
Referring to FIGS. 3, 4, and 6A and 6B, the position sensing assembly 24 is
comprised of a U-shaped support bracket 75 mounted to the base 13. The
U-shaped support bracket 75 has a bracket forward wall 77 and a rear wall
79. Preferably, the bracket 75 is mounted to a base support wall 81 by any
conventional means. It is noted that in the subsequent description,
certain specific elements are presented as part of more than one assembly.
A shaft 83 is rotatively mounted to extend between the bracket walls 77 and
79 by any conventional means such as by a bearing assembly. A drive gear
85 is fixably mounted to the shaft 83 at one end. The motor 42 has a
output gear 87 which is in constant mesh with the drive gear 85 for
causing the shaft 83 to rotate under the influence of the motor 42. A
position lever 89 which includes a envelope facing surface 91, camming
surface 93, and sensor tab 95, and further includes slots 97, 98 and 99,
is slidably mounted on hubs 101, 102 and 103 formed on the rear wall 79 of
the bracket 75. The position lever 89 is mounted to the rear wall 79 such
that the hubs 101, 102 and 103 ride within the respective slots 97, 98 and
99. A cam 105 is eccentrically mounted to the shaft 83 such that the
camming periphery of the cam 105 is opposite the camming surface 93 of the
position lever 89. A spring 107 is detachably mounted to the position
lever at one end and to a formed tab 109 in the rear wall 79 at the other
end. The spring biases the position lever 89 such that the camming surface
93 is biased against the cam surface of cam 105.
Referring to FIGS. 3, 4, and 7A and 7B, mounted to the forward bracket wall
77 is an envelope stop lever 120 which includes an envelope facing surface
122, channeled main section 124, a collared tab 126 mounted within the
channel section 124, a cam follower surface 127 and an interlock tab 128.
The stop lever 120 is pivotally mounted on a hub 130 which is formed in
the forward bracket wall 77. A spring 132 which has one end attachably
mounted to a tab 134 formed on the rearward bracket wall 77 and the other
end attachably mounted to the collared tab 126 biases the camming surface
127 against the cam 135. A locking lever 136 which includes a locking tab
138 and 140 for securing the locking tab 128 of the envelope stop lever
120 between the locking tabs 138 and 140 of the locking lever 136. The
locking lever 136 also includes a camming surface 142 opposite the cam 135
and a formed support ring 144 which is pivotally mounted to a tab 146
formed in the forward bracket wall 77. A spring 148 which is detachably
mounted at one end to a tab 149 and at its other end to the envelope
locking lever 136 is mounted for biasing the locking lever 136 in the
direction of the cam 135.
Referring to FIGS. 3, 4, and 8A, the platen roller assembly 26 includes a
linking arm assembly 201 comprising a first link section 203 having a
receiving channel 205 and a second section 207 having a portion matingly
received in the receiving channel 205 of the first linking section 203.
One end 208 of the first linking section 203 is eccentrically mounted
around the shaft 83. A spring 210 having tis respective ends detachably
mounted in the first and second sections of the linking arm 203 and 207,
respectively, biases the second section 207 within the receiving channel
205 of the first link section 203. The exposed end of the second section
207 includes a hub 212. A second linking arm assembly 214 is constructed
identical to the linking assembly 201 and is eccentrically mounted in
cooperative alignment with the linking arm assembly 201 on the shaft 83.
A pivot link assembly, generally indicated as 218, is mounted to a shaft
216 which is rotatively mounted between the rearward and forward bracket
walls 77 and 79, respectively. The pivot link assembly 218 includes a
first link plate 220 pivotally mounted around shaft 216 at one point and
pivotally mounted around the hub 212 at another point. A second link plate
222 is pivotally mounted around the shaft 216 at one point and includes a
slot 224 wherein the hub 212 rides therein. A spring hook 223 is formed in
the first link plate 220 and a spring hook 225 is formed in the second
link plate 222. A spring 227 has its respective ends fastened around the
respective spring hooks 223 and 225 in a conventional manner. A second
pivot link assembly 226, identical to the pivot link assembly 218, is
pivotally mounted to the shaft 216 in spaced apart relationship to the
pivot link assembly 218. A platen roller shaft 228 is rotatively mounted
by any conventional means to the link plates 220 of the respective pivot
link assemblies, 218 and 226. A platen roller 230 is fixably mounted
around the platen roller shaft 228, between the pivot link assemblies, 218
and 226.
A pressure roller shaft 232 is rotatively mounted by any conventional means
to the link plates 222 of the respective pivot link assemblies 218 and
226. Pressure rollers 234 are fixably mounted around the pressure roller
shaft 232 in spaced apart relationship. The pressure rollers 234 are
aligned generally opposite an ejection plate 233 fixably mounted on the
registration wall 17 and extending laterally therefrom. A drive shaft 236
having a spool 238 fixably mounted to one end is responsive to the motor
44. A spool gear arrangement 240 which includes a hub 242 rotatively
mounted around the shaft 216, a spool 244 fixably mounted to the hub 242.
A gear 246 is fixably mounted to shaft 216. A gear 248 is fixably mounted
to the shaft 232 and a gear 250 is fixably mounted around the shaft 228.
The gear 246 is constant mesh with gear 248 and 250, and an endless belt
252 extends around the spools 238 and 244.
Referring to FIGS. 1 and 4, a thermal drive cassette assembly, generally
indicated as 300, is comprised of a mounting platform 301 of any suitable
construction. The mounting platform 301 is fixably mounted, by any
conventional means, to the back side of the registration wall 17. A tape
motor 46 is fixably mounted to the mounting platform 301, by any suitable
conventional means. The output shaft 303 of the drive motor 46 has a drive
gear 305 fixably mounted to the output shaft 303 of the drive motor 46. A
conventional double gear set 307 having a first gear 309 in constant mesh
with the drive gear 305 and a second gear 311 rotatively mounted to the
back side of the registration wall 17. A conventional double idle gear set
313 having first gear 315 in constant mesh with the gear 311 and a second
gear 317 is rotatively mounted by any conventional means to a gear hub
319. The gear hub 319 is fixably mounted to the mounting platform 317 by
any conventional means and rotatively supports the idle gear set 313 by
any suitable conventional means. A registration wall aperture 312 is
formed in the registration wall 17. A conventional bearing hub assembly
323 is fixably mounted to the back side of the registration wall 17
aligned to the aperture 321. A tape drive shaft 325 extends through the
aperture 321 rotatively supported by the bearing hub assembly 323. A gear
327 is fixably mounted by any conventional means to one end of the tape
drive shaft 325 in constant mesh with the gear 317. A tape drive spool 329
is fixably mounted by any conventional means around a portion of the tape
drive shaft 325.
A tape idle assembly, generally indicated as 331, is mounted to the back
side of the registration wall 17 aligned to a registration wall aperture
333. The tape idle assembly includes a convention one way clutch and shaft
assembly of any suitable construction fixably mounted to the back side of
the registration wall 17 aligned to the aperture 333. The assembly 335
includes an idle shaft 337 extending through the aperture 333. A tape idle
spool 339 is fixably mounted by any conventional means around a portion of
the idle shaft 337.
An encoding assembly, generally indicated as 341, is fixably mounted to a
mounting spindle 343 which is fixably mounted to the back side of the
registration wall 17, by any suitable conventional means, aligned to a
registration wall aperture 345. The encoding assembly 341 includes collar
347 and a input shaft 349. A mating male shaft 351 is received by the
shaft 349 such that the male shaft 351 can experience limited axially
displacement within the shaft 349 and such that the male shaft rotatively
drive the shaft 349 such as by any suitable conventional mating
longitudinal gears arrangement. A spring 353 is placed around the shaft
351 and an end cap gear 355 is fixably mounted by any conventional means
to the shaft 351 within the aperture 345.
The tape cassette 21 is comprised of a cassette housing 400 having a drive
spool 402. The drive spool has formed axial extending gear teeth 404. The
drive spool 402 is rotatively mounted by suitable conventional means in
the cassette housing 400 to be axially aligned to a opening 406 in the
rear wall 408 of the housing 400. The gear teeth 404 of the drive spool
402 are configured to be mating to axial gear teeth 330 formed on the
periphery of the tape drive spool 329. In like manner to drive spool 402,
the cassette housing includes idle spool 339 having axial extending gear
teeth 340 rotatively mounted to the rear wall 408 aligned to an opening
414 in the rear wall 408. The gear teeth 412 are configured to be mating
to axial gear teeth 412 formed on the periphery of the tape idle spool
410. An encoding roller 416 is rotatively mounted in the cassette rear
wall 408, by any suitable conventional means, having a short shaft 418
extending through the rear wall 408 and into the aperture 345 in the
registration wall 17. A gear 420 is fixably mounted to one end of the
short shaft 418 to be in constant mesh with the gear 355 of the encoding
assembly 341. A plurality drag post 421, 422, 423, 424 and 425 are
strategically mounted fixably by any conventional means to the cassette
rear wall 408. The cassette housing 400 further has a cassette opening 426
and is mounted between upper clamp 428 and lower clamp 430 which extend
from the registration wall 17.
Referring to FIG. 3, the platen roller 230 has a length 2L and a radius of
R at the center. The radius of the platen roller 230 has a linear surface
transition to a end radius of (R+h). In the preferred embodiment of the
present invention, the platen roller is comprised of a 25 to 35 durometer
cellular urethane. The preferred dimensions.
______________________________________
Length (2L) 3.000 inches
Center Radius (R)
0.4245 inches
End Radius (R + h)
0.4845 inches
Taper Angle 2.3 degrees
______________________________________
Referring to FIGS. 1, 3, and 8A, 8B and 8C, the function of the thermal
postage meter 11 is to accept an envelope 25, print an indicia using
thermal transfer print technology, and eject the envelope 25 from the
meter 11. The feed direction of the meter 11 is from left to right as
viewed in FIG. 1. The platen roller 230 feeds the envelope 25 at a
constant rate and supplies the print head 19 sufficient backing pressure
needed for transfer of thermal ink from the ribbon to the envelope 25
during the print cycle. The microcontroller 30 is programmed to instruct
the print controller 38 to actuate the heating elements of the print head
19 synchronous to displacement of the envelope 25 to produce a postal
image or other desired image.
As the platen roller 230 feeds the envelope 25, it also feeds the thermal
transfer ribbon. Therefore, use of the platen roller 230 for ejection
would lead to wasted ribbon. The ejection rollers 234 are used to feed the
envelope out of the meter 11 after printing.
As previously described, the thermal transfer ribbon feeds around a
urethane wrapped encoder roller 416 inside the cassette 21. As the ribbon
feeds, the friction of the ribbon against the encoder roller 416 causes it
to turn. The encoder roller 416 has a gear 420 which protrudes from the
back side of the cassette and couples with a mating gear 355 in the meter
11. The mating gear 355 turns an optical encoder 341 which communicates
with the microcontroller 30 for monitoring ribbon motion.
Referring particularly to FIGS. 8A, 8B and 8C, the feed system consists of
the platen roller 230 and ejection rollers 234. These rollers are provided
with independent control of the envelope 25. They are mounted on a linking
assembly 218 and 226 in a manner to produce a rocker type action which
pivots about a fixed location, shaft 216. In the home position (FIG. 8A),
the pressure rollers 234 are above the feed deck 15 and the platen roller
230 is below the feed deck. The envelope stop lever 120 and envelope
position lever 89 are above the feed deck in the path of the envelope 25.
The shaft 83 is positioned at 0 degrees rotation. It should be readily
apparent that the deck 15 is provided with suitable located openings to
accommodate the motion of the platen roller 230, pressure rollers 234,
position lever 89 and stop lever 120.
An envelope 25 is placed onto the feed deck 15 by the operator and inserted
into the feed throat. The envelope 25 hits the spring loaded position
lever 89 and stop lever 120 which is retained by a locking lever 136. The
purpose of the stop finger 120 is to keep the envelope 25 from feeding too
far through the print path and also to assure proper alignment of the
envelope 25. The position lever 89 is displaced by the envelope 25 and
actuates the sensor 106 mounted to the base 24 in response to the
displacement of sensor tab 95. In response to actuation of the sensor 106,
the microcontroller 30 begins the print cycle. When the rip position lever
89 is pushed forward about 4 mm, it unblocks an optical sensor 106. The
microcontroller signals the motor 42 to rotate shaft 83 in a clockwise
direction. The cam shaft 83 contains 2 independent cams 135 and 105 which
drive the stop lever 120 and the position lever 89, respectively, out of
the feed path. The stop lever cam 135 first rotates the lock lever 138 out
of the way. The shaft 83 then continues rotating to move the spring loaded
stop lever 120 out of the feed path. The position lever cam 105 directly
drives the position lever 89 from the path. The stop lever 120 and
position lever 89 are completely out of the paper path after 180 degrees
of shaft 83 rotation.
Concurrently with disengagement of levers 89 and 120, the eccentric shaft
83 rotation causes the spring loaded links 203 and 207 to move the
pressure rollers 234 out of the feed path and the platen roller 230 toward
the envelope 25. The platen roller 230 continues moving toward the
envelope 25 until it closes the envelope 25 between the platen roller 230
and the print head 19 capturing the thermal ribbon therebetween. Depending
on the envelope 25 thickness, the platen roller 230 will meet the envelope
25 at different points in the rotation on the shaft 83. The pressure
rollers 234 may still be above the feed deck. The shaft 83 will then
continue to rotate, causing the links 203 and 207 to separate further and
both the link extension springs 210 and the ejection springs 227 to apply
a load to the envelope 25. When the shaft 83 has rotated 180 degrees, the
pressure rollers 234 are out of the feed path and the platen roller 30 is
fully engaged with the envelope. Printing can not begin.
As mentioned, the shaft 83 acts on and 208, the stop cam 127, the trip
finger cam 105 and a set of flags 504. The flags 504 trigger the
microcontroller 30 when the shaft 83 has rotated 180 degrees. In the most
preferred embodiment, the shaft 83 is driven by a DC brush-type gear motor
42 via a set of gears. When the flag 504 signals the microcontroller 30
that it is time to stop the shaft 83 rotation, the motor 42 is
electronically braked.
Once the platen roller 230 has fully engaged the envelope 25, the drive
motor 44 and the ribbon drive motor 46 start under the direction of the
microcontroller 30. It is noted that the motor 44 turns both the platen
roller 230 and the pressure rollers 234. However, the pressure rollers is
not in the supply path so it has no affect on the envelope 25. Upon
initiation of the print cycle, the envelope 25 and ribbon begins to feed
as the motor 44 is brought up to speed. Printing then starts by loading
data to the print head from the print head controller 38 under the command
instruction of the microcontroller 30 at a constant rate. The speed is
monitored and controlled through the conventional motor encoder (not
shown) on the motor 44. In the most preferred embodiment of the present
invention, the printing operation takes about 425 ms.
While printing, the ribbon is driven through the print nip by the motion of
the envelope 25. The ribbon take-up motor 46 winds up the ribbon on the
take-up core and provides even tension without pulling the ribbon through
the print EMP of the motor 46 is monitored in the preferred embodiment.
Changes in the back EMF indicate quantity of ribbon and the ribbon drive
is modified accordingly by the microcontroller 30. In addition, a sharp
change in the back EMF of the motor indicates that the ribbon is broken
after the print hear or the ribbon has stopped, in either case, the
microcontroller 30 aborts.
While printing, the ribbon is driven through the print be maintained. The
ribbon is fed through a roller 416 and post 421 which provide drag to the
ribbon through the friction of the ribbon against the roller 416 and post
421. A light clutch load is provided by conventional clutch 335 on the
ribbon supply core to provide tighter wrap of the ribbon around the roller
416 and post 421. The ribbon encoder 341 is turned by the friction of the
ribbon moving past the roller 416. The decoder motion 341 is monitored by
the microcontroller 30 to determine if the ribbon breaks before reaching
the print head or if the ribbon runs out, in which case, the
microcontroller will abort. In addition, the encoder 341 can be used to
monitor the speed of the ribbon, and therefore the envelope 25, through
the print nip.
When printing has been competed, the shaft 83 rotates an additional 180
degrees back to its original home position. The linking arm assembly 201
becomes a solid assembly which pushes the pressure rollers 234 against the
envelope 25. Since a lighter load is needed for ejection than for
printing, the spring 210 becomes the only active spring. Again, flags 504
on the shaft 83 interrupt a optical sensor 506 to indicate 180 degrees of
rotation. This 180 degree rotation engages the pressure rollers 234 and
disengages the platen roller 230. During the rotation, the stop lever 120
and position lever 89 are also released to extend above the feed deck. Due
to their very light spring load, the levers 89 and 120 will ride along the
bottom of the envelope 25 until it clears the platen roller 230.
The motor 44 continues to drive rollers 230 and 234. At this point,
however, the platen roller 230 becomes inactive because it is below the
feed deck. At the same time, the ribbon motor 46 is stopped. When the
pressure rollers 234 engage they feed the envelope 25 from the printer at
2 to 3 times the print speed in the preferred embodiment. Once the
envelope 25 clears the print nip, the stop lever and position lever, 120
and 89, respectively, return to their home position. The drive motor 44 is
stopped and the process is complete.
The above description described the preferred embodiment of the invention
and should not be viewed as limiting. The scope of the invention is set
forth in the appendix claims.
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